Anumeha mows lawns. She charges an initial fee and a constant fee for each hour of work. The variable $f$ models Anumeha's fee (in dollars) for working $t$ hours. $f=6+12t$ What is Anumeha's initial fee? $\$$
Solution: Before Anumeha works any amount of time, the hours worked, $t$, is $0$, and her total fee is equal to her initial fee. We can calculate the fee: $\begin{aligned} f&=6+12t\\\\ f&=6+12(0) \\\\ f&=6+0 \\\\ f&= 6\end{aligned}$ Anumeha's initial fee is $\$6$.